This application claims priority to prior application JP 2002-040936, the disclosure of which is incorporated herein by reference.
The present invention relates to a scroll compressor.
In general, a scroll compressor includes a movable scroll driven to make an orbital motion, a fixed scroll defining working spaces, i.e. compression chambers, cooperatively with the movable scroll, and a rotation preventing mechanism for the movable scroll. For the purpose of ensuring seal tightness between the movable scroll and the fixed scroll, JP-A-S63-129182, for example, discloses a scroll compressor wherein a back pressure chamber is formed at the back of an end plate of a movable scroll, and high-pressure refrigerant gas being compressed is conducted into the back pressure chamber via a through hole formed at the center of the end plate of the movable scroll. The disclosed scroll compressor is expected to prevent refrigerant gas being compressed from leaking through sliding portions between a spiral wrap of the movable scroll and an end plate of a fixed scroll and between a spiral wrap of the fixed scroll and the end plate of the movable scroll during operation of a compressor.
In the disclosed scroll compressor, however, because substantially the whole of a space at the back of the end plate of the movable scroll, excluding those portions adjacent to the periphery of the end plate, serves as the back pressure chamber, it is not possible to cool relevant portions using sucked refrigerant gas. Specifically, in an open type compressor that is driven by an external driving source such as a vehicular engine, it is not possible to cool a shaft seal device arranged at the back of a movable scroll using sucked refrigerant gas, or in a hermetic compressor driven by a built-in electric motor, it is not possible to cool the electric motor and its associated components disposed at the back of a movable scroll using sucked refrigerant gas. Consequently, there is a possibility of lowering of durability of the shaft seal device or the motor etc. and thus lowering of reliability of the compressor.
It is therefore an object of the present invention to provide a scroll compressor that improves a prevention effect against leakage of refrigerant gas being compressed, without impeding cooling of relevant portions using sucked refrigerant gas.
Other objects of the present invention will become clear as the description proceeds.
According to one aspect of the present invention, there is provided a scroll compressor comprising a housing, a fixed scroll, a movable scroll placed between the housing and the fixed scroll to define a compression chamber in cooperation with the fixed scroll; and an Oldham ring slidably interposed between the housing and the movable scroll to regulate a motion of the movable scroll, the Oldham ring having a space forming a back pressure chamber between the housing and the movable scroll, the movable scroll having a through hole allowing the compression chamber to communicate with the back pressure chamber.